Well here is Stapp in his own words, as opposed to someone else’s interpretation of his view (taken from the very end of that link I gave):
This situation is concordant with the idea of a powerful God that creates the universe and its laws to get things started, but then bequeaths part of this power to beings created in his own image, at least with regard to their power to make physically efficacious decisions on the basis of reasons and evaluations. I see no way for contemporary science to disprove, or even render highly unlikely, this religious interpretation of quantum theory, or to provide strong evidence in support of an alternative picture of the nature of these ‘free choices’. These choices seem to be rooted in reasons that are rooted in feelings pertaining to value or worth. Thus it can be argued that quantum theory provides an opening for an idea of nature and of our role within it that is in general accord with certain religious concepts, but that, by contrast, is quite incompatible with the precepts of mechanistic deterministic classical physics. Thus the replacement of classical mechanics by quantum mechanics opens the door to religious possibilities that formerly were rationally excluded. This conception of nature, in which the consequences of our choices enter not only directly in our immediate neighborhood but also indirectly and immediately in far-flung places, alters the image of the human being relative to the one spawned by classical physics. It changes this image in a way that must tend to reduce a sense of powerlessness, separateness, and isolation, and to enhance the sense of responsibility and of belonging. Each person who understands him-or herself in this way, as a spark of the divine, with some small part of the divine power, integrally interwoven into the process of the creation of the psycho-physical universe, will be encouraged to participate in the process of plumbing the potentialities of, and shaping the form of, the unfolding quantum reality that it is his or her birthright to help create. (Henry Stapp, “Minds and Values in the Quantum Universe,” in Information and the Nature of Reality , ed. by Paul Davies and Niels Henrik Gregersen (2010)).
There are several other quotes of his there that contradict that Springer’s version of Stapp’s stance.
The wave function itself is immaterial. That was not the kicker though because that’s not any different from saying that all of mathematics is immaterial. The kicker was that the scientists themselves could effect the outcome depending on their choices. This is where, Stapp in the quote above, talks about people having been bequeathed some power.